Studies are continuing on the role of HLA gene products in recognition of foreign antigen by human T cells. Studies in this project with the hapten TNP complements the studies of influenza virus in project Z01-CB-05078 I. The principal effector mechanism under investigation is cell-mediated cytotoxicity, but proliferation is also used as a measurement of T cell response. Conditions have been optimized to allow use of frozen peripheral blood lymphocytes as responders, which will facilitate further immunogenetic analysis. More careful analysis of the TNP-restriction antigens by direct lysis and blocking confirms involvement of B cell antigens, probably including, but not restricted to, HLA-DR. Monoclonal antibody inhibition studies are in progress as another tool in defining the restriction antigens involved.